A Birmingham Islamic school which featured in a damning TV documentary has received malicious calls threatening to firebomb the building.

Darul Uloom Islamic High School, in Small Heath, will be closed until next month amid safety fears over an investigation which filmed a hate-filled speech to pupils.

The Channel 4 Dispatches documentary, Lessons in Hatred and Violence, showed a preacher making remarks about Hindus and ranting: “Disbelievers are the worst creatures”.

The school’s head of curriculum, Mujahid Aziz, said since the documentary had been shown on Monday, the school has been targeted by “a barrage of hate calls” and that students felt “victimised”.

Mr Aziz said: “Even before the programme started, we were shocked that we were getting a barrage of hate calls and emails threatening with the most disgusting language which I can’t really say, and they were threatening to bomb the place.

“The student themselves feel in the spotlight, they feel victimised. This is the very kind of thing that creates extremism.”

Teachers insisted footage shown in the documentary was an “isolated incident” involving a 17-year-old senior student talking to pupils and said the teenager was expelled last August.

Mr Aziz added the school was also drafting a complaint to broadcasting watchdog Ofcom.

A spokesman for Channel 4 defended the programme, saying the comments made in the film “speak for themselves”.

The spokesman said: “Our investigation exposed numerous adults in positions of authority at the school on many different occasions teaching pupils as young as 11 years of age contempt for other religions and wider society.

"These include speakers, teachers, senior teachers and visiting ‘Maulanas’. The school continues to fail to respond to address these issues.

“The programme clearly raises concerns about those in positions of responsibility in these schools – not the pupils who attend.”

A West Midlands Police spokesman said: "A number of messages believed to be of a malicious nature have been reported to police. Enquiries are currently underway.

"As a partnership West Midlands Police, Children's Social Care and the Department for Education who govern independent schools will be reviewing all footage filmed by Channel Four and Hardcash Productions to assess any concerns regarding the wellbeing and teaching of children shown in the programme."